Heat exchanger for cooling

ABSTRACT

A plurality of heat exchange plates  12  are laminated on each other so that surfaces of the heat exchange plates  12  can be directed in the direction of gravity, protruding portions  14  composing refrigerant passages  15, 16,  in which refrigerant for cooling air flows, are formed on the heat exchange plates  12  in such a manner that the protruding portions  14  extend in the direction of gravity, an air passage is formed between the plurality of heat exchange plates  12,  a plurality of contact ribs  17  protruding into the air passage are formed on the heat exchange plates  12,  and the pitches P 1  and P 2  in the direction of gravity between the plurality of contact ribs  17  in the lower region on the leeward side are made to be smaller than pitch P 3  in an upper region on the leeward side and a windward side region.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to a heat exchanger for cooling in which condensed water is generated when air is cooled. For example, the present invention relates to a heat exchanger preferably used in an air conditioner for vehicle use.

2. Description of the Related Art

The official gazettes of JP-A-11-287580 and 2002-48491, which will be referred to as Patent Documents 1 and 2 hereinafter, propose the following heat exchanger. A protruding portion composing an inner passage, in which cooling fluid such as refrigerant flows, is integrally formed on a heat exchange plate. This protruding portion is made to function as a turbulence generator which obstructs a straight flow of air outside the heat exchange plate so as to generate turbulence in the air flow.

According to this heat exchanger, when an air flow is made to be a turbulent flow, it is possible to enhance a heat transfer coefficient on the air side. Therefore, it is possible to abolish a fin member such as a corrugated fin which is provided in a common fin-and-tube-type heat exchanger. Accordingly, this heat exchanger can be manufactured by only press forming and brazing the heat exchange plate.

When the protruding portion composing the inner passage is arranged in such a manner that the protruding portion extends in the direction of gravity (the vertical direction), condensed water can drop smoothly down a surface of the protruding portion extending in the direction of gravity. Therefore, as compared with a conventional fin-and-tube-type heat exchanger, this heat exchanger drains well.

However, according to an experimental investigation made by the present inventors, according to the prior art described in Patent Documents 1 and 2, there is a tendency that the condensed water splashes out on the leeward side. It was found that the water splash preventing property of the heat exchanger of the prior art is not sufficiently high.

SUMMARY OF THE INVENTION

In view of the above problems, the object of the present invention is to enhance the water splash preventing property of a heat exchanger for cooling air.

In the present invention, the present inventors devised a technical means for accomplishing the above object according to the experimental knowledge described as follows.

FIG. 11 is a schematic illustration showing a mechanism of generating a water splash in the heat exchanger described in Patent Documents 1 and 2. The mechanism of generating a water splash is divided into the following two main types.

(1) A water splash caused by a bridging water film

(2) A water splash caused by dropping water-drops.

In the heat exchanger described in Patent Documents 1 and 2, a protruding portion 14 extending in the direction of gravity is integrally formed on a heat exchange plate 12, and an inner passage, in which the cooling fluid flows, is formed inside this protruding portion 14. Contact ribs 17 are integrally formed at a plurality of positions in the longitudinal direction (the direction of gravity) on the side portion of the protruding portion 14 on the heat exchange plate 12. When the top portions of these contact ribs 17 are contacted to each other under pressure and joined, the heat exchange plates 12 can be positively joined to each other.

First, referring to the left column shown in FIG. 11, the water splash generation mechanism (1), which is caused by an explosion of a bridging water film, will be explained below. In a portion of the heat exchange plate 12, in which the contact rib 17 is formed, an area in contact with the condensed water, which is generated on a surface of the heat exchange plate 12, is increased. Therefore, the generated condensed water is temporarily held by the contact rib 17. Accordingly, the condensed water collects in a portion in which the contact rib 17 is formed.

This condensed water is moved by gravity to a lower portion of the contact rib 17, and a bridging water film D is formed which connects a flat base plate portion 13 of the heat exchange plate 12 with a top portion of the adjoining protruding portion 14 in such a manner that the bridging water film D is formed into a bridge shape.

When the condensed water is supplied from an upper portion of the contact rib 17, this bridging water film D grows as shown by item (b) in the drawing. When the weight of this bridging water film D is increased, the bridging water film D is pulled downward by gravity. Further, when the bridging water film D receives the wind pressure of a flow of air blown onto the heat exchange plate, the bridging water film D is pulled to the leeward side. Due to the foregoing, the bridging water film D bulges to both sides of the lower portion and on the leeward side of the flow of air. In this case, the thickness of the bridging water film D is very slightly reduced. In item (b), a direction of the wind is from the distant side of the surface of the drawing to the viewer's side.

In this case, when a pitch (interval) in the direction of gravity between a plurality of contact ribs 17 is large, a bulge in the bridging water film D reaches the limit of maintaining the water film. Therefore, as shown in item (c), the bridging water film D explodes and changed into fine water-drops E. Accordingly, when the bridging water film D explodes on the leeward side in the most downstream portion in the air passage of the heat exchanger, the thus generated water-drops E are conveyed by a flow of air and splashed out on the leeward side of the heat exchanger.

In this connection, the aforementioned phenomenon is caused not only in the lower portion of the contact rib 17 but also in other portions. However, the aforementioned phenomenon usually occurs in the lower portion of the contact rib 17.

Next, referring to the right column shown in FIG. 11, the water-splash-generation mechanism (2), which is caused by dropping of water-drops, will be explained below. At the time of a heavy-load cooling operation in which the amount of the generated condensed water is large or at the time of explosion of the bridging water film described above, as shown in item (d), water-drops F, the amount of which is relatively large, tend to be generated. In this case, water-drops F, the amount of which exceeds a predetermined value, drop from the lower side of the contact rib 17. Therefore, as shown in item (e), the water-drops F collide with the lower contact rib 17.

In this case, when a pitch (interval) in the direction of gravity between a plurality of contact ribs 17 is large, the potential energy of the water-drop F is high. Therefore, the intensity of impact energy becomes high when a water-drop F collides with the lower contact rib 17. Accordingly, the water-drop F is energetically splashed on the leeward side due to the repulsion power at this time.

Accordingly, when the water-drop F drops and splashes on the leeward side on the most downstream side of a flow of air in the air passage of the heat exchanger, the water-drop F is conveyed by the flow of air as it is and splashes on the leeward side of the heat exchanger. In this connection, the above phenomenon tends to be caused in a lower region on the leeward side, in which the amount of water is large, of the heat exchanger. This phenomenon, in which the condensed water drops and splashes, is also caused in a lower side tank portion of the heat exchanger.

As can be understood from the analysis of the water splashing mechanism described before, the following fact was discovered. In the heat exchanger in which a plurality of protrusions such as contact ribs (17) are dispersedly arranged in the direction of gravity of the heat exchange plate (12), a pitch (interval) in the direction of gravity between the plurality of protrusions greatly affects the splashing of the water-drops.

In order to accomplish the above object, according to a first characteristic of the present invention, there is provided a heat exchanger for cooling, in which condensed water is generated by cooling air, comprising:

a heat exchange plate (12) composing a fluid passage (15, 16) in which cooling fluid for cooling the air flows, wherein

a plurality of heat exchange plates (12) are laminated on each other so that faces of the heat exchange plates (12) can be directed in the direction of gravity,

an air passage (18), in which the air flows, is formed between the plurality of heat exchange plates (12),

a plurality of protrusions (17) protruding into the air passage (18) are formed on the heat exchange plate (12), and

the heat exchange plate (12) includes a leeward side region in which a pitch in the direction of gravity between the plurality of protrusions (17) is not more than a predetermined value and also includes a windward side region in which a pitch in the direction of gravity between the plurality of protrusions (17) is larger than that of the leeward side region or the protrusions (17) are not formed.

Due to the above understanding, it is possible to adopt a structure in which a pitch in the direction of gravity between a plurality of protrusions (17) in the leeward region of the heat exchange plate (12) is smaller than that of the windward region. Therefore, in the leeward region, before a bulge in the bridging water film D in the water splash generation mechanism (1) reaches the limit of holding a water film, the bridging water film D comes into contact with the next protrusion. Therefore, the bridging water film D is changed into a relatively large water-drop-shape (grain-shape). Therefore, it is possible to prevent the bridging water film from exploding. Accordingly, it is possible to prevent water-drops from splashing out on the leeward side of the heat exchanger due to an explosion of the bridging water film.

When a pitch in the direction of gravity between a plurality of protrusions on the leeward side is reduced, the potential energy of the water-drops is reduced. Therefore, the collision energy at the time of collision of the water-drops with the lower side protrusions can be reduced. As a result, splashing can be sufficiently suppressed at the time of dropping of the water-drops in the water splash generation mechanism (2) described before.

As a result of the foregoing, it is possible to sufficiently enhance the water splash preventing property of the heat exchanger for cooling air.

According to a second characteristic of the present invention, there is provided a heat exchanger for cooling in which condensed water is generated by cooling air, comprising:

a heat exchange plate (12) composing a fluid passage (15, 16) in which cooling fluid for cooling the air flows, wherein

a plurality of heat exchange plates (12) are laminated on each other so that faces of the heat exchange plates (12) can be directed in the direction of gravity,

an air passage (18), in which the air flows, is formed between the plurality of heat exchange plates (12),

a plurality of protrusions (17) protruding into the air passage (18) are formed on the heat exchange plate (12), and

the heat exchange plate (12) includes a lower region on the leeward side in which a pitch in the direction of gravity between the plurality of protrusions (17) is not more than a predetermined value and also includes an upper region on the leeward side in which a pitch in the direction of gravity between the plurality of protrusions (17) is larger than that of the lower region on the leeward side or the protrusions (17) are not formed.

In this connection, the condensed water generated on a surface of the heat exchange plate (12) tends to collect in a lower region on the leeward side of the heat exchange plate (12) as it is affected by the gravity and the wind pressure of a flow of air.

According to the second characteristic described above, it is possible to adopt a structure in which a pitch in the direction of gravity between a plurality of protrusions (17) in the lower region on the leeward side of the heat exchange plate (12) is reduced. Therefore, it is possible to effectively prevent water-drops from splashing from the lower region on the leeward side of the heat exchange plate of the water splash generation mechanisms (1), (2).

According to a third characteristic of the present invention, there is provided a heat exchanger for cooling in which condensed water is generated by cooling air, comprising:

a heat exchange plate (12) composing a fluid passage (15, 16) in which cooling fluid for cooling the air flows, wherein

a plurality of heat exchange plates (12) are laminated on each other so that faces of the heat exchange plates (12) can be directed in the direction of gravity,

an air passage (18), in which the air flows, is formed between the plurality of heat exchange plates (12),

a plurality of water-holding portions (17) for holding the condensed water attached to the heat exchange plate (12) are provided on the heat exchange plate (12), and

a pitch in the direction of gravity between the plurality of water-holding portions (17) is set at least in the leeward side region of the heat exchange plate (12) so that the condensed water can gradually flow down between the plurality of water-holding portions (17), at a predetermined wind speed of the air, without splashing, in the direction of gravity.

Due to the foregoing, at least in the leeward region of the heat exchange plate (12), the condensed water can be made to flow down between a plurality of water-holding portions (17) without being splashed downward in the direction of gravity. Therefore, it is possible to effectively prevent water-drops from splashing from the leeward region of the heat exchange plate (12).

In the third characteristic described above, the water-holding portion can be specifically constituted by protrusions (17) protruding from the heat exchange plate (12) into the air passage (18).

In the present invention, specifically, the protruding portions (14) are formed on the heat exchange plate (12) and are extended in the direction of gravity. Inside the protruding portions (14), a fluid passage (15, 16), in which cooling fluid flows, is formed.

Due to the foregoing, the condensed water can be made to smoothly flow down along the side portion extending in the direction of gravity of the protruding portion (14). Therefore, water can drain well with respect to the entire heat exchanger.

The protrusions (17) in each characteristic described above may be formed in the side portion of the protruding portion (14). Alternatively, the protrusions (17) in each characteristic described above may be formed on the side of the protruding portion (14) at a predetermined interval.

In the present invention, specifically, the protrusions (17) are formed in such a manner that they are respectively protruded from the two adjoining heat exchange plates (12) into the air passage (18), and the protrusions (17) of the two adjoining heat exchange plate (12) are joined to each other.

Due to the foregoing, when a plurality of heat exchange plates (12) are joined to each other, joining can be executed when a pushing force is given to the joining faces of a plurality of heat exchange plates (12). Accordingly, the plurality of heat exchange plates (12) can be positively joined to each other.

In the present invention, specifically, a pitch in the direction of gravity between the plurality of protrusions (17) at least in the leeward region is reduced on the downward side in the direction of gravity.

Due to the foregoing, it is possible to effectively prevent water-drops from splashing from the lower region on the leeward side of the heat exchange plate (12) in which the condensed water tends to collect.

In the present invention, a pitch in the direction of gravity between a plurality of protrusions (17) at least in the lower region on the leeward side on the heat exchange plate (12) is set to be not more than 30 mm.

In this case, the phrase “at least in the lower region on the leeward” means a region on a lower side of the central portion in the direction of gravity in the leeward region of the heat exchange plate (12).

According to an experimental investigation made by the present inventors, the following was confirmed. When a pitch in the direction of gravity between a plurality of protrusions (17) is made to be not more than 30 mm, as exemplarily shown in FIG. 7 later, the wind speed at which water-drops start to splash is enhanced to a value not less than a predetermined value. Therefore, it is possible to ensure a water-drop splash preventing property which is sufficiently high for practical use.

Further, the following was confirmed. When a pitch in the direction of gravity between a plurality of protrusions (17) is made to be not more than 18 mm, the water-drop splash preventing property can be further enhanced.

Furthermore, the following was confirmed. When a pitch in the direction of gravity between a plurality of protrusions (17) is made to be not less than 7 mm, an increase in the ventilating resistance of the heat exchanger can be suppressed to be a low value.

Incidentally, the reference numerals in parentheses, to denote the above means, are intended to show the relationship of the specific means which will be described later in an embodiment of the invention.

The present invention may be more fully understood from the description of preferred embodiments of the invention set forth below, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view showing an evaporator of the first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a refrigerant passage structure of the evaporator of the first embodiment.

FIG. 3 is a sectional view taken on line I-I in FIG. 1.

FIG. 4 is a sectional view taken on line J-J in FIG. 1.

FIG. 5 is a front view showing a heat exchange plate of the first embodiment.

FIG. 6 is a schematic illustration for explaining the behavior of condensed water in the first embodiment.

FIG. 7 is a graph showing a result of an experiment regarding the speed at which water-drops start splashing in an evaporator and also showing a result of an experiment regarding the ratio of an increase in the ventilating resistance.

FIG. 8 is a front view showing a heat exchange plate in the second embodiment.

FIG. 9 is a front view showing a heat exchange plate in the third embodiment.

FIG. 10 is a front view partially showing a heat exchange plate in which a contact rib is shown in the fourth embodiment.

FIG. 11 is a schematic illustration for explaining a water splash generating mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The first embodiment will be explained below. In the first embodiment, the present invention is applied to an evaporator used in an air conditioner for vehicle use. First, the overall structure of an evaporator 10 used for air conditioning of a vehicle will be explained below. FIG. 1 is an exploded perspective view showing an outline of the overall structure of the evaporator, and FIG. 2 is an exploded perspective view in which a passage indicated by an arrow representing a refrigerant passage is added to FIG. 1. FIG. 3 is a sectional view taken on line I-I in FIG. 1, and FIG. 4 is a sectional view taken on line J-J in FIG. 1. FIGS. 3 and 4 show a cross-sectional lamination structure of a heat exchange plate 12. FIG. 5 is a front view showing a single body of the heat exchange plate 12.

The overall structure of the evaporator shown in FIGS. 1 and 2 may be essentially the same as that shown in Patent Documents 1 and 2 described before. The evaporator 10 is constituted by a cross-flow opposed type heat exchanger in which a direction of the flow A of air to be air-conditioned and a direction of the flow B of refrigerant flowing in the heat exchange portion (the vertical direction in FIGS. 1 and 2) make a right angle with each other and, further, a passage on the upstream side (the inlet) of the refrigerant is located on the downstream side (on the leeward side) of the air flow direction and a passage on the downstream side (the outlet) of the refrigerant is located on the upstream side (on the windward side) of the air flow. In this connection, in the evaporator 10, the air is a fluid to be cooled (external fluid), and the refrigerant is a fluid to cool the air (internal fluid).

In this evaporator 10, a core portion 11 for exchanging heat between the air to be conditioned and the refrigerant is constituted by a large number of heat exchange plates 12 being laminated in the direction (the lateral direction in the drawing) perpendicular to the air flowing direction A. More specifically, the large number of heat exchange plates 12 are laminated on each other so that the plate surfaces can extend in the direction of gravity.

In this connection, in both end portions of the heat exchange plates 12, that is, in upper and lower end portions of the heat exchange plates 12, tank portions 20 to 23, described later, are formed. No air passes through portions in which these tank portions 20 to 23 are formed. Therefore, the core portion 11 is constituted by an intermediate portion of the heat exchange plate 12 except for the tank portions 20 to 23 located at the upper and lower end portions.

Each heat exchange plate 12 is formed by means of press forming of a thin metallic plate. Specifically, a double faced clad material plate, on which an A4000 aluminum brazing material plate is clad onto both sides of an A3000 core material plate of aluminum, is formed by means of press forming. Wall thickness t (shown in FIGS. 3 and 4) of the heat exchange plate 12 is very small and, for example, wall thickness t of the heat exchange plate 12 is approximately 0.15 mm. The plan shape of each heat exchange plate 12 is substantially rectangular. The outer dimensions of all the heat exchange plates 12 are the same.

Next, a specific shape of the heat exchange plate 12 will be explained below by referring to FIGS. 3 to 5. On each heat exchange plate 12, protruding portions 14 are formed from a flat base plate portion 13 by means of embossing. These protruding portions 14 are formed into a rib-shape continuously extending in the longitudinal direction (the direction of gravity) B of the heat exchange plate 12 and in parallel with each other. A cross-sectional shape of each protruding portion 14 is formed into a substantial semicircle in the example shown in FIG. 4. However, the cross-sectional shape of each protruding portion 14 may be formed into, for example, a substantial trapezoidal shape, the corner portions of which are chamfered. Alternatively, the cross-sectional shape of each protruding portion 14 may be formed into another shape.

An embossed height Rh (shown in FIG. 3) of the protruding portion 14 is set at ½ of the tube pitch Tp (shown in FIGS. 3 and 4). The embossed height Rh of the protruding portion 14 is a height including the wall thickness t of the heat exchange plate 12. The tube pitch Tp is an interval of arranging the heat exchange plates 12. As an example, the tube pitch Tp is 3 mm.

An inside space of the protruding portion 14 constitutes an inner passage. Specifically, the inside space of the protruding portion 14 constitutes a refrigerant passage 15, 16 in which the low pressure side refrigerant flows after it has passed through a decompressing means such as an expansion valve in a refrigerating cycle. In this case, the evaporator 10 is arranged so that the longitudinal direction B of the heat exchange plate 12 is directed in the direction of gravity. Therefore, the longitudinal direction B of the heat exchange plate 12 is directed to the direction of gravity.

At a central position of the protruding portion pitch Rp (shown in FIG. 3), which is an interval between the protruding portions on one heat exchange plate 12, each protruding portion 14 of the other heat exchange plate 12, which is joined to the one heat exchange plate 12, is located. Therefore, when a pair of heat exchange plates 12, 12 are opposed to each other in such a manner that the protruding portions of the heat exchange plates 12, 12 are directed outside and these heat exchange plates 12, 12 are contacted and joined with each other, an inner face side of each protruding portion 14 of one heat exchange plate 12 is tightly closed by a wall face of the base plate portion 13 of the other heat exchange plate 12.

Accordingly, between the inner face of each protruding portion 14 and the base plate portion 13 of the heat exchange plate 12 on the opposite side, it is possible to constitute refrigerant passages 15, 16. In this case, the refrigerant passage 15 constitutes a leeward side refrigerant passage which is located in the downstream side region in the air flowing direction A, and the refrigerant passage 16 constitutes a windward side refrigerant passage which is located in the upstream side region in the air flowing direction A.

In this connection, in FIGS. 3 and 4, the numbers of the embossed protruding portions on the pair of heat exchange plates 12, 12 are, respectively, five. On the other hand, in FIGS. 1 and 2, the numbers of the embossed protruding portions 14 on one of the pair of heat exchange plates 12, 12 are, respectively, six, and numbers of the embossed protruding portions 14 on the other of the pair of heat exchange plates 12, 12 are respectively five. The above case is shown in the drawing. However, of course, the number of the embossed protruding portions 14, that is, the number of the refrigerating passages 15, 16 can be increased or decreased according to the performance necessary for the evaporator 10 or according to the outer shape of the evaporator 10.

On the other hand, at both end portions in the longitudinal direction B of the heat exchange plates 12, two tank portions 20 to 23, which are divided in the heat exchange plate width direction (the air flow direction A), are respectively formed. That is, at the upper end portion of the heat exchange plates 12, two tank portions 20, 22 are formed. At the lower end portion of the heat exchange plates 12, two tank portions 21, 23 are formed.

These tank portions 20 to 23 are formed by means of embossing each heat exchange plate 12 in the same direction as that of the protruding portion 14. An embossed height of each tank portion 20 to 23 is the same as the embossed height Rh of the protruding portion 14. It is ½ of the tube pitch Tp (shown in FIGS. 3 and 4). Top portions of the tanks 20, 23, which are adjacent to each other, are contacted and joined to each other.

Concerning these tank portions 20 to 23, the leeward side tank portions 20, 21 are communicated with each other by the leeward side refrigerant passage 15, and the windward side tank portions 22, 23 are communicated with each other by the windward side refrigerant passage 16. In this connection, the embossed height Rh of the protruding portion 14 may not be the same as the embossed height of each tank portion 20 to 23 but the embossed height Rh of the protruding portion 14 may be somewhat increased or decreased with respect to the embossed height of each tank portion 20 to 23.

Each protruding portion 14 includes: a first portion extending substantially in the direction of gravity; and a second portion extending from this first portion in a direction perpendicular to the direction of gravity. The first portion hardly obstructs a flow of the condensed water. On the other hand, the second portion is given a position and a shape so that a flow of the condensed water can be easily obstructed by the second portion as compared with the first portion. The position and the shape of the second portion are determined so that the condensed water in a waterdrop shape can be easily held as compared with the first portion. In this embodiment, the first portion is proposed by a refrigerant passage which is a straight rising portion. The second portion is proposed by a contact rib 17 which is a protruding portion extending from the rising portion in the lateral direction.

In each protruding portion 14, a contact rib 17 is formed which is composed of a small protrusion protruding from the side portion in the width direction of the heat exchange plate (in the direction A of an air flow). Specifically, in order to form an air passage 18 (shown in FIG. 3) described later, in one (the lower side heat exchange plate 12 in FIG. 4) of the heat exchange plates 12, 12 which are opposed to each other, a large number of contact ribs 17 are integrally formed so that they can protrude from the side portion of the protruding portion 14 on the leeward side. In the other heat exchange plate 12 (the upper side heat exchange plate 12 in FIG. 4) of the heat exchange plates 12, 12 which are opposed to each other, a large number of contact ribs 17 are integrally formed so that they can protrude from the side portion of the protruding portion 14 on the windward side. In this connection, FIG. 5 shows a heat exchange plate 12 in which a large number of contacts 17 are integrally formed so that they can be protruded from the side portion of the protruding portion 14 on the leeward side.

As shown by the portion Z in the enlarged view of FIG. 1, a plane shape of this contact rib 17 is a smooth semicircle. Of course, the plane shape of this contact rib 17 can be formed out of a plane shape except for the semicircle, for example, the plane shape of this contact rib 17 can be formed out of a rectangle or a polygon, the corner portions of which are chamfered.

As shown in FIG. 4, an embossed height of the contact rib 17 is the same as the embossed height Rh of the protruding portion 14. Alternatively, the embossed height of the contact rib 17 is somewhat larger than the embossed height Rh of the protruding portion 14. As shown in FIG. 4, an inner space of the contact rib 17 is communicated with a space of the refrigerant passage 15, 16 formed inside each protruding portion 14.

Top portions of the contact ribs 17 of two heat exchange plates 12 to be joined are contacted with each other as shown in FIG. 4. While the contact portion of the contact ribs 17 is being given a pushing force in the direction of laminating the heat exchange plates, the entire evaporator 10 is integrally brazed.

Due to the foregoing, in the intermediate portion (the portion in which the refrigerant passage 15, 16 is formed) of the heat exchange plate 12 except for the tank portions 15 to 18 at both end portions in the longitudinal direction, the base plate portions 13 of the heat exchange plates 12 can be entirely, positively contacted with each other and the contact face of the base plate portions can be excellently brazed. Due to the foregoing, it is possible to prevent leakage, of the refrigerant from the refrigerant passage 15, 16, which is caused by a defective brazing.

In order to entirely and positively make the base plate portions of the heat exchange plates 12 come into contact with each other, a large number of contact ribs 17 are dispersedly formed in the longitudinal direction (the direction of gravity) of the heat exchange plate. In this embodiment, as shown in FIG. 5, a countermeasure for preventing water from splashing is taken at the contact rib 17 which is formed on the side portion of the protruding portion 14 located at a position on the extreme leeward side in a plurality of protruding portions 14 extending in the direction of gravity.

That is, in the vertical direction (the direction of gravity) of the protruding portion 14 on the extreme leeward side, in the lower region G, the number of the contact ribs 17 to be arranged is increased and the pitch P1, P2 in the direction of gravity between the contact ribs 17 is made to be much smaller than the pitch P3 in the other regions (the upper region on the leeward side and the windward side region). Further, in the lower region G on the leeward side, the pitch P2 on the lower side is made to be much smaller than the pitch P1 on the upper side. The pitches P1, P2, P3 in the direction of gravity of the contact ribs 17 are distances between the centers of the contact ribs 17 which are adjacent to each other.

In this connection, in FIG. 5, two protruding portions 14, which are in the five protruding portions 14 extending in the vertical direction, are formed into a shape which is bent and formed into a wave-shape. The reason why two protruding portions 14 are formed into a wave-shape is that a vortex generated at the rear end side of the air flow of the protruding portion 14 is divided so as to the reduce noise generated by a flow of air in the same manner as that of Patent Document 2.

In this connection, when two heat exchange plates 12 are arranged in such a manner that the protruding face sides of the two heat exchange plates 12 are directed outside from each other and that the protruding portions 14 of the two heat exchange plates 12 are shifted from each other in the width direction of the heat exchange plate and that the base plate portion 13 of the two heat exchange plates 12 are contacted with each other, each protruding portion 14 is positioned at a recess face portion formed by the base end portion 13 of the other heat exchange plate 12 which is adjacent.

As a result, a gap is necessarily formed between the top portion on the protruding face side of each protruding portion 14 and the base plate portion 13 (the recess face portion) of the other heat exchange plate 12 which is adjacent. This gap corresponds to the embossed height Rh of the protruding portion 14. As shown in FIG. 3, an air passage 18 is continuously formed and snakes, in a wave-shape, all over the length in the width direction (the direction of the air flow A) of the heat exchange plate 12.

Accordingly, a flow of air, which flows as shown by the arrow A in FIG. 3, flows in the air passage 18 between two heat exchange plates 12 while the flow of air snakes in a wave-shape as shown by the arrow A₁ in FIG. 3.

As described above, the tank portions 20 to 23 are embossed in the same direction as that of the protruding portions 14 and, further, both end portions in the longitudinal direction of the recess shape formed by embossing the protruding portion 14 are set so that both end portions of the recess shape can continue to the embossed recess shape of the tank portion 20 to 23. Therefore, both end portions of the refrigerant passage 16 on the windward side are communicated with the upper and lower tank portions 22, 23 on the windward side. Both end portions of the refrigerant passage 15 on the leeward side are communicated with the upper and lower tank portions 20, 21 on the leeward side.

In this case, the leeward side tank portion 20 and the windward side tank portion 22 on the upper side of the heat exchange plate respectively define and form an independent refrigerant passage. The leeward side tank portion 21 and the windward side tank portion 23 on the lower side of the heat exchange plate respectively define and form an independent refrigerant passage.

At the central top portion of each tank portion 20 to 23, the communicating opening 20 a to 23 a is open. Therefore, when the embossed top portions of the tank portions 20 to 23, which are adjacent to each other, are contacted and joined to each other, these communicating openings 20 a to 23 a can be communicated with each other.

Due to the foregoing, in the lateral direction (the laminating direction of the heat exchange plates) shown in FIGS. 1 and 2, the refrigerant passages of the tank portions 20 to 23 can be communicated with each other between the adjoining heat exchange plates.

Next, explanations will be made into portions in which the refrigerant is supplied to and discharged from the core portion 11. As shown in FIGS. 1 and 2, on both end sides in the laminating direction of the heat exchange plates, end plates 24, 25, the size of which is the same as that of the heat exchange plate 12, are arranged. Both the end plates 24, 25 are respectively formed into a flat plate shape and come into contact with the protruding face side of the tank portions 20 to 23 of the heat exchange plates 12 and join to the heat exchange plate 12.

A refrigerant inlet pipe 24 a and a refrigerant outlet pipe 24 b are joined to the hole portions arranged close to the upper end portion of the left end plate 24 shown in FIGS. 1 and 2. This refrigerant inlet pipe 24 a is communicated with a communication opening 20 a at the top of the leeward side tank portion 20 which is formed at an upper end portion of the left heat exchange plate 12. This refrigerant outlet pipe 24 b is communicated with a communication opening 22 a at the top of the windward side tank portion 22 which is formed at an upper end portion of the left heat exchange plate 12.

The above left end plate 24 is formed out of a double-faced aluminum clad plate in the same manner as that of the heat exchange plate 12. The left end plate 24 is joined to the refrigerant inlet pipe 24 a and the refrigerant outlet pipe 24 b by means of brazing. The right end plate 25 is formed out of one-faced clad plate in which only a side to be joined to the heat exchange plate 12 is clad with brazing material.

Into the refrigerant inlet pipe 24 a, a two-phase refrigerant, of gas and liquid, the pressure of which is low because the refrigerant is decompressed by a decompressing means such as an expansion valve not shown, flows into the refrigerant inlet pipe 24 a. On the other hand, the refrigerant outlet pipe 24 b is connected to a compressor suction side not shown and guides the gas-phase refrigerant, which has been evaporated by the evaporator 10, onto the compressor suction side.

In a group of a large number of heat exchange plates 12 which are laminated in the lateral direction in FIGS. 1 and 2, into the leeward side refrigerant passage 15 formed inside the protruding portions 14, the refrigerant flows from the refrigerant inlet pipe 23. Therefore, the group of a large number of heat exchange plates 12 constitute an inlet side refrigerant passage in the refrigerant passage in the entire evaporator.

On the other hand, into the windward side refrigerant passage 16 formed inside the protruding portions 14, the refrigerant passing through the refrigerant passage 15 on the leeward side (the inlet side) flows. Therefore, the refrigerant is made to flow to the refrigerant outlet pipe 24 b. Accordingly, the windward side refrigerant passage 16 constitutes an outlet side refrigerant passage.

Next, referring to FIG. 2, explanations will be made into the refrigerant passage of the entire evaporator 10. In the tank portions 20 to 23 located at the upper and the lower end portion of the evaporator 10, the leeward side tank portions 20, 21 constitute a refrigerant inlet side tank portion, and the windward side tank portions 22, 23 constitute a refrigerant outlet side tank portion.

The tank portion 20 on the refrigerant inlet side on the upper side on the leeward side is partitioned into the left passage (the passage on the region X side) shown in FIG. 2 and the right passage (the passage on the region Y side) shown in FIG. 2 by a partitioning portion (not shown) arranged at the intermediate position (the boundary portion between the regions X and Y) in the laminating direction of the heat exchange plate 12.

In the same manner, the tank portion 22 on the refrigerant outlet side on the upper side on the windward side is partitioned into the left passage (the passage on the region X side) shown in FIG. 2 and the right passage (the passage on the region Y side) shown in FIG. 2 by a partitioning portion (not shown) arranged at the intermediate position. These partitioning portions can be simply constituted in such a manner that only the heat exchange plate located at the intermediate position, which is in the heat exchange plates described before, is made up of a shutoff-wall-shaped (a blanking-cover-shaped) heat exchange plate in which the communication opening portion of the top portion of the tank portion 20, 22 is closed.

According to the constitution of the refrigerant passage shown in FIG. 2, the two-phase, gas and liquid, refrigerant of low pressure, which has been decompressed by the expansion valve, flows from the refrigerant inlet pipe 24 a into the inlet side tank portion 20 on the upper side on the leeward side as shown by the arrow “a”. This passage of the inlet side tank portion 20 is divided into the regions X and Y on the left and right by a partitioning portion not shown in the drawing. Therefore, the refrigerant flows only into the passage of the left region X of the inlet side tank portion 20.

In the left region X in FIG. 2, the refrigerant flows down in the refrigerant passage 15 formed by the leeward side protruding portion 14 of the heat exchange plate 12 as shown by the arrow “b” and enters the inlet tank portion 21 on the lower side. Then, the refrigerant is moved in the inlet side tank portion 21, on the lower side to the right region Y illustrated in FIG. 2, as shown by the arrow “c”. Then, the refrigerant flows upward in the refrigerant passage 15 formed by the leeward side protruding portion 14 of the heat exchange plate 12 in the right region Y as shown by the arrow “d” and enters the right region Y of the inlet side tank portion 20 on the upper side.

In this case, the communication opening 20 a of the inlet side tank portion 20 of the right-most heat exchange plate 12 is communicated to the communication opening portion 22 a of the outlet tank portion 22 located on the upper side of the most right heat exchange plate 12 by a communication passage (not shown, indicated by the arrow f) formed close to the upper end portion of the right end plate 25.

Accordingly, the refrigerant, which has flowed into the passage of the right region Y of the inlet side tank portion 20 on the upper side, flows to the right as shown by the arrow “e” and then passes through a communication passage (not shown) in the neighborhood of the upper end portion of the right end plate 25 as shown by the arrow “f”. Then, the refrigerant flows into the right region Y of the outlet side tank portion 22 on the upper side.

In this case, the passage of the outlet side tank portion 22 is divided into the regions X and Y on the left and right by a partitioning portion not shown. Therefore, the refrigerant flows only into the passage of the right region Y of the outlet side tank portion 22 as shown by the arrow “g”. Next, the refrigerant flows down from the right region Y of the tank portion 22 into the refrigerant passage 16 formed by the windward side protruding portion 14 of the heat exchange plate 12 as shown by the arrow “h” and enters the right region Y of the outlet side tank portion 23 on the lower side.

The refrigerant flows from the right region Y in the outlet side tank portion 23 on the lower side as shown by the arrow “i”. Therefore, the refrigerant flows into the left region X shown in FIG. 2. After that, the refrigerant flows upward in the refrigerant passage 16 formed by the windward side protruding portion 14 of the heat exchange plate as shown by the arrow “i”. Therefore, the refrigerant enters the left region X of the outlet side tank portion 22 on the upper side. The refrigerant flows to the left in this outlet side tank portion 22 as shown by the arrow “k” and flows out from the refrigerant outlet pipe 24 b to outside the evaporator.

In the evaporator 10 shown in FIGS. 1 and 2, the refrigerant passage is constituted as described above. Components (12, 24, 25, 24 a, 24 b) shown in FIGS. 1 and 2 are laminated being contacted with each other. While this laminating condition (the assembling condition) is being held by an appropriate jig, the assembled body is conveyed into a heating furnace for brazing and heated to the melting point of the brazing material. In this way, the assembled body is integrally brazed. Due to the foregoing, assembling of the evaporator 10 is completed.

Next, an action of the above evaporator 10 will be explained below. The evaporator 10 is accommodated in an air conditioning unit case not shown in such a manner that the vertical direction of accommodating the evaporator 10 in the unit case is the same as the vertical direction shown in FIGS. 1 and 2. When a blower for air conditioning is operated, air flows in the direction of the arrow A.

When the compressor incorporated into the refrigerating is set in motion, two-phase, gas and liquid, refrigerant on the low pressure side, which has been decompressed by an expansion valve not shown, flows in the passages indicated by the arrows “a” to “k” shown in FIG. 2. On the other hand, due to a gap formed between the protruding portions 14, which are protruded on the outer face side of the heat exchange plate 12, and the base plate portion 13, the air passage 18 snakes in a wave-shape all over the length, in the width direction (the direction of the air flow A), of the heat exchange plate as shown by the arrow A1 in FIG. 3.

As a result, air which flows as shown by the arrow A flows in the air passage 18 between two heat exchange plates 12 while the flow of air is snakes in a wave-form as shown by the arrow A1. The refrigerant takes the latent heat of evaporation from the air flow and evaporates. Therefore, the air to be conditioned, which is blown in the direction of the arrow A, is cooled and changed into a flow of cold air.

In this case, when the inlet side refrigerant passage 15 is arranged on the leeward side with respect to the direction A of the flow of the conditioned air and when the outlet side refrigerant passage 16 is arranged on the windward side with respect to the direction of the flow of the conditioned air, the inlet and the outlet of the refrigerant with respect to the flow of air can be maintained in a counter-current flow relationship.

Further, on the air side, the direction A of the air flow is perpendicular to the longitudinal direction (the refrigerant flow direction B in the refrigerant passage 15, 16) of the protruding portion 14 of the heat exchange plate 12, and the protruding portion 14 forms a protruding heat exchange face which protrudes perpendicularly to the air flow. Accordingly, the air flow is obstructed by the protruding shape of the protruding portion 14 extending perpendicularly into the air flow. Further, when the air flow moves over the protruding shape of the protruding portion 14, a passage area of the air flow locally expands and contracts, and this expansion and contraction are repeated. Therefore, the air flow is disturbed and becomes a turbulent flow. Accordingly, a heat transfer coefficient on the air side surface of the protruding portion 14 can be remarkably enhanced.

In this connection, the evaporator 10 is actually used by being arranged so that the longitudinal direction of the heat exchange plate 12 can be the same as the direction of gravity as shown in FIGS. 1 and 2. In use, when a flow of air passes through in the air passage 18 (shown in FIG. 3) formed between two heat exchange plates 12 while the flow of air is snaking as shown by the arrow A1, the flow of air collides with a front side of the protruding face of the protruding portion 14 extending in the direction of gravity and generates condensed water. The thus generated condensed water is moved to the rear side of the protruding face of the protruding portion by wind pressure. The condensed water drops downward due to gravity on the rear side of the protruding face of the protruding portion 14.

In this case, contact ribs 17 constituted by semicircular small protrusions are dispersedly arranged at a plurality of portions in the direction of gravity of the side portion of the protruding portion, and the contact ribs 17 of two heat exchange plates 12, which are opposed to each other, are joined to each other. Therefore, in this portion in which the contact ribs 17 are formed, a contact area with the condensed water is increased and the condensed water is temporarily caught so as to hold the condensed water. That is, this portion functions as a water-holding portion. The condensed water attached onto the upper face side of the contact rib 17 gradually moves downward to the lower side of the contact rib 17.

The above behavior of the condensed water becomes remarkable on the leeward side of the heat exchange plate 12, and in the lower region, due to the influence of the wind pressure of the air flow and also due to gravity. Accordingly, the two water splashing mechanisms (1) and (2) shown in FIG. 11 appear on the leeward side of the heat exchange plate 12 and in the lower region. Therefore, water tends to splash on the leeward side of the heat exchange plate 12 and in the lower region.

Therefore, in the present embodiment, in the direction of gravity (the vertical direction) of the protruding portion 14 on the extreme leeward side, the number of the contact ribs 17 to be arranged is increased in the lower region G, and the pitch P1, P2 in the direction of gravity between the contact ribs 17 is sufficiently reduced as compared with the pitch P3 in the other region (the upper region on the leeward side and the region on the windward side).

Due to the foregoing, even in the case where condensed water, which has collected on the lower side of the contact rib 17, forms a bridging water film D due to the water splash generating mechanism (1), as the pitch P1, P2 is small, before bulging of the bridging water film D reaches a limit of maintaining the film state, the bridging water film D comes into contact with the next contact rib 17 and forms a relatively large water-drop (grain-shape). Therefore, it is possible to prevent the bridging water film from exploding.

Even in the case where a water-drop drops by the water splash generating mechanism (2), as the pitches P1 and P2 are small, an intensity of potential energy of the water drop is low. Therefore, an intensity of collision energy of the water-drop is low at the time of colliding with the contact rib 17 on the lower side. As a result, as shown in FIG. 6, the dropping water-drop can be temporarily held, without splashing, by the contact rib 17 on the lower side. Therefore, the dropping water-drop can be successively made to flow downward. Accordingly, splashing of water can be sufficiently suppressed when the water-drop drops down.

As a result, the water splash preventing property can be sufficiently enhanced in the case of a so-called fin-less type evaporator 10 in which the core portion 11 is constituted only by the heat exchange plate 12.

In this embodiment, in the lower region G arranged on the leeward side, the pitch P2 on the lower side is made to be much smaller than the pitch P1 on the upper side. Therefore, water splashing can be more effectively prevented in the lowermost portion on the leeward side.

Next, by referring to the experimental data shown in FIG. 7, the water splash preventing effect of the present embodiment will be specifically explained below. The axis of abscissa shown in the graph of FIG. 7 expresses a pitch in the direction of gravity between the contact ribs 17 on the extreme leeward side of the heat exchange plate 12. In this connection, in FIG. 5, the pitch in the direction of gravity between the contact ribs 17 on the extreme leeward side of the heat exchange plate 12 is changed by P2<P1<P3. However, in the experiment shown in FIG. 7, the pitch in the direction of gravity between the contact ribs 17 on the extreme leeward side of the heat exchange plate 12 is made to be constant all over the region in the direction of gravity. Accordingly, the contact rib pitch of the axis of abscissa of FIG. 7 is a pitch to be applied to all the contact ribs 17 on the extreme leeward side of the heat exchange plate 12.

The axis of ordinate of the graph shown in FIG. 7 is a wind speed at the start of water splashing from the evaporator 10. This wind speed at the start of water splashing from the evaporator 10 is measured as follows. A piece of paper is arranged on the leeward side of the evaporator 10 being opposed, and a wind speed of the flow of air from the evaporator at the point of time when water is attached to this piece of paper is measured so that it can be determined to be a water splashing start speed. Accordingly, the higher this water splash start speed, the more excellent the water splash preventing property.

The axis of ordinate of the graph shown in FIG. 7 expresses a ratio (%) of the increase in the ventilation resistance of the evaporator 10. Specifically, when the contact rib pitch=50 mm is determined to be a reference pitch, the axis of ordinate of the graph shown in FIG. 7 expresses a ratio (%) of the increase in the ventilation resistance with respect to the evaporator 10 in which this reference pitch=50 mm is adopted.

In this connection, the experimental conditions on the air side are described as follows. The temperature of air sucked by the evaporator is 30° C., and the relative humidity RH is 70%. On the other hand, the experimental conditions on the refrigerant side are described as follows. The pressure of the high pressure refrigerant on the upstream side of the decompressing device is 1.64 MPa, the degree of supercooling is 5° C., the pressure of the low pressure refrigerant on the outlet side of the evaporator 10 is 0.18 MPa, and the degree of superheating is 10° C. The maximum width M of the root portion of the contact rib 17 is 3 mm (Refer to the portion Z in FIG. 1.).

In FIG. 7, the solid line (1) is a wind speed at the start of water splash. When the contact rib pitch is reduced, the water splash start wind speed is increased and the water splash preventing property can be enhanced.

In this case, when the contact rib pitch is set at a value of not more than 30 mm, the water splashing start wind speed can be increased to a value not less than 3.8 m/s. This value of the water splashing start wind speed=3.8 m/s is substantially the same as the water splashing start wind speed of a conventional fin and tube type evaporator in which corrugated fins are used. Therefore, when the contact rib pitch is set at a value not more than 30 mm, it is possible to ensure the same water splashing preventing property as that of the conventional fin and tube type evaporator.

When the contact rib pitch is set at a value not more than 18 mm, it is possible to enhance the water splashing start wind speed to a value of not less than 5 m/s. Therefore, as compared with the conventional fin and tube type evaporator, the water splash preventing property can be sufficiently enhanced.

On the other hand, a ratio of the increase in the ventilation resistance of the evaporator shown by the broken line (2) starts increasing in the neighborhood of the contact rib pitch=30 mm. The ratio of the increase in the ventilation resistance of the evaporator suddenly increases in the neighborhood of the contact rib pitch=7 mm. Accordingly, when a lower limit of the contact rib pitch is set at 7 mm and the contact rib pitch is set at a value not less than 7 mm, it is possible to suppress a ratio of the increase in the ventilation resistance to be a low value of not more than several %.

Next, the second embodiment will be explained below. In the first embodiment, the number of the contact ribs 17 is increased only in the lower region G on the extreme leeward side of the heat exchange plate 12, and the pitch P1, P2 in the direction of gravity between the contact ribs 17 in the lower region G on the leeward side is reduced as compared with the pitch P3 in the upper region on the leeward side. However, in the second embodiment, as shown in FIG. 8, the number of the contact ribs 17 in the lower region G and the upper region H on the leeward side of the heat exchange plate 12 is increased to more than the number of the contact ribs 17 in the intermediate portion in the direction of gravity, and the contact rib pitch in the lower region G and the upper region H is reduced as compared with the contact rib pitch in the intermediate portion in the direction of gravity.

In this connection, as a variation of the first and the second embodiment, the contact rib pitch in all regions in the gravity direction of the extreme leeward side region of the heat exchange plate 12 may be smaller than the contact rib pitch in the windward side region. In any of the above variation and the second embodiment, the same water splash preventing effect as that of the first embodiment can be exhibited.

Next, the third embodiment will be explained below. FIG. 9 is a view showing the third embodiment. In this embodiment, the heat exchange plate 12 is formed into a shape which is symmetrical with respect to the center line S of the longitudinal direction (the direction of gravity), that is, the heat exchange plate 12 is formed into a shape which is symmetrical with respect to the vertical direction. According to this embodiment, it is possible to prevent a problem in which the heat exchange plate 12 is assembled while being turned upside down in the assembling process of the evaporator.

Next, the fourth embodiment will be explained below. In the first embodiment, the contact rib 17 is directly formed on the side portion of the protruding portion for composing the refrigerant passage, and the inside of the contact rib 17 is communicated with the inside of the protruding portion 14. However, in the fourth embodiment, the contact rib 17 is independently formed at a predetermined interval from the side portion of the protruding portion. Accordingly, in the fourth embodiment, the inside of the contact rib 17 is not communicated with the inside of the protruding portion 14. Even when the above structure is adopted, the original role of the contact rib 17 can be ensured and the water splash preventing effect can be exhibited in the same manner. In this case, the original role of the contact rib 17 is to push the base plate portions 13 of the heat exchange plates 12 to each other at the time of brazing.

In this connection, in the fourth embodiment, a plane shape of the contact rib 17 is formed into a circle. However, it should be noted that the plane shape of the contact rib 17 is not limited to the circle. The plane shape of the contact rib 17 may be formed into the another shape such as an ellipse.

The present invention is not limited to the above specific embodiment. Variations can be made as described below.

(1) In the above embodiments, the base plate portion 13 of the heat exchange plate 12 is formed into only a flat face. However, a fin portion, which protrudes into the air passage 18, may be integrally formed in this base plate portion 13. For example, this fin portion is formed being embossed into a C-shape. As air flows on both faces of an inner and an outer face, it is possible to greatly increase a heating surface area on the air side. Further, when the fin portion is formed, a temperature boundary layer can be made thin. Therefore, the heat transfer coefficient on the air side can be enhanced in the base plate portion 13.

(2) In the above embodiments, explanations are made into the evaporator 10 having the contact ribs 17 for pushing the base plate portions 13 of the heat exchange plates 12 at the time of brazing. However, the following constitution may be adopted. In the evaporator, the contact ribs 17 are abolished. Instead of the contact ribs 17, protrusions, by which a gap is interposed between one heat exchange plate 12 and the other heat exchange plate 12, are formed on one heat exchange plate 12, and these protrusions are not joined onto a surface of the other heat exchange plate 12. In the evaporator constituted as described above, a pitch in the direction of gravity of these protrusions may be set according to the present invention.

(3) In the above embodiment, an explanation is given of an example in which the contact ribs 17 are formed in all regions arranged from the leeward side to the windward side of the heat exchange plate 12. However, the condensed water generated on the surface of the heat exchange plate 12 tends to collect at the lower region on the leeward side of the heat exchange plate 12 due to gravity and the wind pressure of an air flow. Therefore, the following constitution may be adopted. Protrusions such as contact ribs 17 in the leeward side region and the windward side region of the heat exchange plate 12 are abolished, and protrusions such as contact ribs 17 are provided only in the lower region on the leeward side of the heat exchange plate 12.

(4) According to the explanations of the above embodiment, the heat exchange plate 12 provides a plate face extending in the vertical direction (the direction of gravity) and, further, the protruding portions 14 are extended in the vertical direction (the direction of gravity). However, the aforementioned arrangement extending in the vertical direction (the direction of gravity) is not necessarily limited to an arrangement in which the vertical direction is accurately perpendicular to the horizontal face. As long as the property of draining the condensed water is not lowered, the heat exchange plates 12 a to 12 c and the protruding portions 14 may be arranged somewhat inclined with respect to the vertical direction. For example, a surface of each heat exchange plate 12 can be inclined with respect to the vertical direction as long as the condensed water can smoothly flow down. Further, even when a surface of the heat exchange plate 12 is vertically arranged, the protruding portions 14 may be formed inclined with respect to the vertical direction.

(5) In the above embodiment, the refrigerant passages (the inner passages) 15, 16 are formed inside the protruding portions 14 when two heat exchange plates 12, which are completely separated from each other, are laminated and joined to each other. However, the refrigerant passages (the inner passages) 15, 16 may be formed inside the protruding portions 14 as follows. One heat exchange plate, the size and shape of which correspond to those of two heat exchange plates of the embodiment described above, is prepared. This one heat exchange plate is folded at the center so that the size of the heat exchange plate can be reduced to ½ and the thus folded heat exchange plate, the size of which is ½, can be put on each other. After that, the thus folded shape of one heat exchange plate is joined. In this way, the refrigerant passages (the inner passages) 15, 16 may be formed inside the protruding portions 14.

That is, in the present invention, the concept “Two heat exchange plates 12 are used as one set.” includes: a case in which two heat exchange plates, which are completely separated from each other, are used and laminated on each other; and a case in which one heat exchange plate is folded at the center so that the size can be reduced to ½ and the thus folded heat exchange plates, the size of which is ½, are put on each other.

(6) In the above embodiment, explanations are made into a case in which the present invention is applied to the evaporator 10 in which a refrigerant at a low temperature on the low pressure side of the refrigerating cycle flows in the refrigerant passages 15, 16 of the heat exchange plates 12. However, the present invention can be applied in the same manner to a heat exchanger for cooling in which another type cooling fluid such as cold water flows in the refrigerant passages 15, 16 of the heat exchange plates 12.

While the invention has been described by reference to specific embodiments chosen for purposes of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention. 

1. A heat exchanger for cooling, in which condensed water is generated by cooling air, comprising: a heat exchange plate composing a fluid passage in which cooling fluid for cooling the air flows, wherein a plurality of heat exchange plates are laminated on each other so that faces of the heat exchange plates can be directed in the direction of gravity, an air passage, in which the air flows, is formed between the plurality of heat exchange plates, a plurality of protrusions protruding into the air passage are formed on the heat exchange plate, and the heat exchange plate includes a leeward side region in which a pitch in the direction of gravity between the plurality of protrusions is not more than a predetermined value and also includes a windward side region in which a pitch in the direction of gravity between the plurality of protrusions is larger than that of the leeward side region or the protrusions are not formed.
 2. A heat exchanger for cooling in which condensed water is generated by cooling air, comprising: a heat exchange plate composing a fluid passage in which cooling fluid for cooling the air flows, wherein a plurality of heat exchange plates are laminated on each other so that faces of the heat exchange plates can be directed in the direction of gravity, an air passage, in which the air flows, is formed between the plurality of heat exchange plates, a plurality of protrusions protruding into the air passage are formed on the heat exchange plate, and the heat exchange plate includes a lower region on the leeward side in which a pitch in the direction of gravity between the plurality of protrusions is not more than a predetermined value and also includes an upper region on the leeward side in which a pitch in the direction of gravity between the plurality of protrusions is larger than that of the lower region on the leeward side or the protrusions are not formed.
 3. A heat exchanger for cooling in which condensed water is generated by cooling air, comprising: a heat exchange plate composing a fluid passage in which cooling fluid for cooling the air flows, wherein a plurality of heat exchange plates are laminated on each other so that faces of the heat exchange plates can be directed in the direction of gravity, an air passage, in which the air flows, is formed between the plurality of heat exchange plates, a plurality of water-holding portions for holding the condensed water attached to the heat exchange plate are provided on the heat exchange plate, and a pitch in the direction of gravity between the plurality of water-holding portions is set at least in the leeward side region of the heat exchange plate so that the condensed water can gradually flow down between the plurality of water-holding portions, at a predetermined wind speed of the air, without splashing, in the direction of gravity.
 4. A heat exchanger for cooling according to claim 3, wherein the water-holding portion is a protrusion protruding from the heat exchange plate into the air passage.
 5. A heat exchanger for cooling according to claim 4, wherein a protruding portion is formed on the heat exchange plate in such a manner that the protruding portion extends in the direction of gravity, the fluid passage is formed inside the protruding portion, and the protrusions are formed on a side portion of the protruding portion.
 6. A heat exchanger for cooling according to claim 4, wherein a protruding portion is formed on the heat exchange plate in such a manner that the protruding portion extends in the direction of gravity, the fluid passage is formed inside the protruding portion, and the protrusions are formed on a side of the protruding portion at a predetermined interval.
 7. A heat exchanger for cooling according to claim 4, wherein the protrusions are respectively protruded from two heat exchange plates, which are adjacent to each other, into the air passage, and the protrusions of the two heat exchange plates, which are adjacent to each other, are joined to each other.
 8. A heat exchanger for cooling according to claim 4, wherein a pitch in the direction of gravity between the plurality of protrusions at least at the leeward side region of the heat exchange plate is reduced when it comes to a lower portion in the direction of gravity.
 9. A heat exchanger for cooling according to claim 4, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on the leeward side of the heat exchange plate is reduced to a value of not more than 30 mm.
 10. A heat exchanger for cooling according to claim 4, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on leeward side of the heat exchange plate is reduced to a value of not more than 18 mm.
 11. A heat exchanger for cooling according to claim 10, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on the leeward side of the heat exchange plate is not less than 7 mm.
 12. A heat exchanger for cooling according to claim 1, wherein a protruding portion is formed on the heat exchange plate in such a manner that the protruding portion extends in the direction of gravity, the fluid passage is formed inside the protruding portion, and the protrusions are formed on a side portion of the protruding portion.
 13. A heat exchanger for cooling according to claim 2, wherein a protruding portion is formed on the heat exchange plate in such a manner that the protruding portion extends in the direction of gravity, the fluid passage is formed inside the protruding portion, and the protrusions are formed on a side portion of the protruding portion.
 14. A heat exchanger for cooling according to claim 1, wherein a protruding portion is formed on the heat exchange plate in such a manner that the protruding portion extends in the direction of gravity, the fluid passage is formed inside the protruding portion, and the protrusions are formed on a side of the protruding portion at a predetermined interval.
 15. A heat exchanger for cooling according to claim 2, wherein a protruding portion is formed on the heat exchange plate in such a manner that the protruding portion extends in the direction of gravity, the fluid passage is formed inside the protruding portion, and the protrusions are formed on a side of the protruding portion at a predetermined interval.
 16. A heat exchanger for cooling according to claim 1, wherein the protrusions are respectively protruded from two heat exchange plates, which are adjacent to each other, into the air passage, and the protrusions of the two heat exchange plates, which are adjacent to each other, are joined to each other.
 17. A heat exchanger for cooling according to claim 2, wherein the protrusions are respectively protruded from two heat exchange plates, which are adjacent to each other, into the air passage, and the protrusions of the two heat exchange plates, which are adjacent to each other, are joined to each other.
 18. A heat exchanger for cooling according to claim 1, wherein a pitch in the direction of gravity between the plurality of protrusions at least at the leeward side region of the heat exchange plate is reduced when it comes to a lower portion in the direction of gravity.
 19. A heat exchanger for cooling according to claim 2, wherein a pitch in the direction of gravity between the plurality of protrusions at least at the leeward side region of the heat exchange plate is reduced when it comes to a lower portion in the direction of gravity.
 20. A heat exchanger for cooling according to claim 1, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on the leeward side of the heat exchange plate is reduced to a value of not more than 30 mm.
 21. A heat exchanger for cooling according to claim 2, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on the leeward side of the heat exchange plate is reduced to a value of not more than 30 mm.
 22. A heat exchanger for cooling according to claim 1, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on leeward side of the heat exchange plate is reduced to a value of not more than 18 mm.
 23. A heat exchanger for cooling according to claim 2, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on leeward side of the heat exchange plate is reduced to a value of not more than 18 mm.
 24. A heat exchanger for cooling according to claim 9, wherein a pitch in the direction of gravity between the plurality of protrusions at least in a lower region on the leeward side of the heat exchange plate is not less than 7 mm. 